Insulin-like growth factor-I, cognition and brain aging.

Aging is associated with a decline in the activity of the growth hormone (GH)/insulin-like growth factor-I (IGF-I) axis. As aging also coincides with a decline in specific cognitive functions and as some of these dysfunctions are also observed in subjects with GH deficiency, it has been hypothesised that a causal relationship exists between the reduction in circulating GH and/or IGF-I and the observed cognitive deficits in the elderly. The present review summarises the available data concerning the possible relation between GH, IGF-I and cognitive performance, and regarding possible underlying pathophysiological mechanisms.